This invention relates to a system for cleaning machined industrial parts. More particularly, it relates to a system for cleaning machining oil, coolants and contaminants from industrial parts.
During the manufacture of industrial parts, the parts are commonly exposed to and contaminated by a wide variety of liquids and chemicals. For example, during the machining process, the parts very commonly become contaminated with machining oil and other hard-to-remove coolants and lubricants at some point in the manufacturing process. The machined parts must be completely cleaned of these machining oils, coolants and/or other contaminants.
One prior solution for cleaning industrial parts contaminated with machining oil and other oil based contaminants is vapor degreasing. Vapor degreasing methods use chemical solvents such as trichloroethylene to remove the contaminants by exposing the parts to vapors of the chemical solvents. Although vapor degreasing has proven to be effective in removing the contaminants from the parts, it is very expensive. The high cost of vapor degreasing is due to the ever increasing cost of the chemicals such as trichloroethylene, the requirements for the environmentally safe disposal of the expended chemicals, and the cleaning of the vapor degreasing system itself. Regulations which are intended to reduce the use of toxic chemicals and to ensure the proper disposal of such waste lead to the increased cost of cleaning industrial parts by vapor degreasing.
Another prior solution for the cleaning of industrial parts is aqueous parts washers. Aqueous parts washers repeatedly wash the parts with combinations of water, soaps and detergents. However, even after washing and rinsing in aqueous parts washers, particularly intricate parts or parts with difficult to remove contaminants can require additional cleaning operations. Furthermore, the soaps and detergents become ineffective after extended use and must be replaced. Likewise, the waste wash water containing the detergents and soaps must be extensively filtered prior to disposal. In addition, the replacement of spent detergents and soaps and the filtration of the waste wash water render the aqueous parts washers very costly to operate. Therefore, the cost of such cleaning systems has proven to be excessive, even though the aqueous based systems are not entirely effective.
Aqueous parts washers typically clean the part or work piece in either of two cleaning modes: spraying or immersion. Those parts washing systems which employ spraying often project the spray through a wire mesh basket or other perforate structure containing the parts. The effectiveness of the spray is diminished by the mesh or perforate structure which impedes the spray prior to contact with the parts.
For example, U.S. Pat. No. 4,353,381 issued to Winters on a cleaning apparatus for automotive parts or the like. The parts are deposited into a wire mesh basket and a cleaning fluid is sprayed onto the parts through the wire mesh basket. As a result, the spray and its cleaning effectiveness is inhibited by the wire mesh basket prior to contacting the parts.
Alternatively, aqueous parts washers commonly employ immersion as the cleaning mode in which the parts are submerged in a cleaning solution bath. In some cases these immersion type washers require the parts to be transferred to a drum in which they are repeatedly tumbled into and out of the bath of cleaning solution. However, during the tumbling process, the bath becomes contaminated and ineffective for cleaning. Worse yet, the parts are exposed to the contaminated bath and the chemicals and other contaminates previously removed from the parts accumulate back onto the parts.
Representative of such immersion type drum washers are U.S. Pat. Nos. 3,134,203 and 3,578,002 issued to Roberts and Rowan, respectively. Each of these patents discloses a system in which the work pieces are tumbled into and out of a cleaning solution or bath. But each of these systems suffer because the bath into which the parts are immersed becomes contaminated with residue previously removed from the parts, thereby diminishing the overall cleaning effectiveness of these systems.
Another form of immersion type washers employ an agitated bath in which the parts are submerged. The parts are typically contained in a basket and immersed in a bath. The bath is agitated, for example by underwater air jets or ultrasound waves, to enhance the cleaning effect. However, the parts are still exposed to a contaminated bath with this type of immersion wash system.
In an effort to improve upon pure immersion type washers or pure spraying type washers, U.S. Pat. Nos. 2,675,011 and 3,302,655, issued to Maddaford and Sasaki, respectively, disclose apparatus for bottle washing which utilizes both spray and immersion modes of cleaning. The bottles are individually retained in compartments or radial carriers on the outer periphery of a rotating disk or drum. The bottles are sequentially sprayed and immersed into a bath as they rotate on the drum or disk. A problem associated with these systems though is a requirement for a complex parts or bottle handling mechanism which loads and removes the bottles. Each bottle must be individually loaded and retrieved from the drum or disk, thereby requiring a complex handling mechanism. A further problem with these systems, is the contamination of the immersion bath as previously described in reference to other immersion type systems. Contaminates and residue previously removed from the bottles or parts accumulate in the bath and can be deposited back onto the bottles or parts which are to be cleaned.